1. Field of the Invention
The present application relates to communication systems. Particularly, these embodiments are directed to allocating communication resources among the plurality of subscribers to a communication system.
2. Related Art
Several solutions have been presented to address the problem of allocating limited communication resources provided by a single node in a communication system among a plurality of subscribers. It is an objective of such systems to provide sufficient resources at the nodes to satisfy the requirements of all subscribers while minimizing costs. Accordingly, such systems are typically designed with the objective of efficient allocation of resources among the various subscribers.
Various systems have implemented a frequency division multiple access (FDMA) scheme which allocates resources to each of the subscribers concurrently. A communication node in such systems typically has a limited bandwidth for either transmitting information to or receiving information from each subscriber in the network at any point in time. This scheme typically involves allocating distinct portions of the total bandwidth to the individual subscribers. While such a scheme may be effective for systems in which subscribers require uninterrupted communication with the communication node, better utilization of the total bandwidth may be achieved when such constant, uninterrupted communication is not required.
Other schemes for allocating communication resources of a single communication node among a plurality of subscribers includes time division multiple access (TDMA) schemes. These TDMA schemes are particularly effective in allocating the limited bandwidth resources of a single communication node among a plurality of subscribers which do not require constant, uninterrupted communication with the single communication node. TDMA schemes typically dedicate the entire bandwidth of the single communication node to each of the subscribers at designated time intervals. In a wireless communication system which employs a code division multiple access (CDMA) scheme, this may be accomplished by assigning to each of the subscriber units all code channels at the designated time intervals on a time multiplexed basis. The communication node implements the unique carrier frequency or channel code associated with the subscriber to enable exclusive communication with the subscriber. TDMA schemes may also be implemented in land line systems using physical contact relay switching or packet switching.
TDMA systems typically allocate equal time intervals to each subscriber in a round robin fashion. This may result in an under utilization of certain time intervals by certain subscribers. Similarly, other subscribers may have communication resource requirements which exceed the allocated time interval, leaving these subscribers under served. The system operator then has the choice of either incurring the cost of increasing the bandwidth of the node to ensure that none of the subscribers are under served, or allowing the under served subscribers to continue to be under served.
Accordingly, there is a need to provide a system and method of allocating communication resources among subscribers to a communication network efficiently and fairly according to a network policy of allocating the communication resources among the subscribers.
An object of an embodiment of the present invention is to provide a system and method for allocating a finite resource of a communication system among a plurality of subscribers.
Another object of an embodiment of the present invention is to provide a system and method for allocating data transmission resources among a plurality of subscribers which have varying capacities to receive data.
It is another object of an embodiment of the present invention to provide a system and method for optimally allocating data transmission resources among a plurality of subscribers subject to a fairness criteria according to a network policy.
It is another object of an embodiment of the present invention to provide a system and method for allocating data transmission resources of a base station among a plurality of remote stations in a wireless communication network.
It is yet another object of an embodiment of the present invention to provide a system and method for enhancing the efficiency of transmitting data to a plurality of subscribers in a variable rate data transmission network by allocating transmission resources to each individual subscriber based upon the rate at which the subscriber can receive transmitted data.
Briefly, an embodiment of the present invention is directed to a resource scheduler in a communication system which includes a common node and a plurality of customer nodes associated with the common node. The common node, at any particular service interval, is capable of providing a finite resource to be seized by one or more engaging customer nodes to the exclusion of any remaining customer nodes. The resource scheduler includes logic for maintaining a weight or score associated with each of the customer nodes, logic for selecting one or more of the remaining customer nodes to seize the finite resource in a subsequent service interval based upon a comparison of the weight associated with each of the selected customer nodes and the respective weights associated with the other remaining customer nodes, and logic for changing the weights associated with the customer nodes to cause an optimal allocation of the finite resource subject to a fairness criteria.
The resource scheduler may maintain the weights associated with each customer node based upon the instantaneous rate at which the customer node can receive data from the common node. The resource scheduler may then favor transmission to the customer nodes having the higher rates of receiving data. By maintaining a weight associated with each of the customer nodes, and selecting individual customer nodes to seize the common node, the scheduler can optimally allocate resources to the customer nodes subject to a fairness criteria.
In the embodiment where the common node provides data transmission resources to the customer nodes, for example, the scheduler may apply weights to the individual customer nodes so as to favor those customer nodes capable of receiving data at higher rates. Such a weighting tends to enhance the overall data throughput of the common node. In another embodiment, the weights are applied in a manner so that the scheduler also complies with the fairness criteria.
In one aspect of the invention, a method of allocating a finite resource in a communication system is provided, the communication system including a common node and a plurality of customer nodes associated with the common node, each of the customer nodes having a requested data rate, wherein during any particular service interval the common node allocates the finite resource to one of the customer nodes to the exclusion of any remaining customer nodes, the method comprising the steps of: maintaining a set of weights having one weight corresponding to each of the customer nodes; identifying a minimum weight M from said set of weights; identifying a subset of said customer nodes having weights less than or equal to the sum of M and an offset K; determining a desirability metric value for each customer node in said subset; selecting, from said subset, a most desired customer node having the greatest desirability metric value; exchanging data between the common node and said most desired customer node through the finite resource and at the data rate associated with said most desired customer node; and changing said set of weights based on said most desired customer node and the data rate associated with said most desired customer node.
In anther aspect of the invention, a wireless transmitter apparatus is provided, comprising: at least one antenna for receiving requested data rate signals from each of a plurality of customer nodes and for directing information signals to said plurality of customer nodes; a channel element for modulating a data signal for transmission through said at least one antenna to each of said plurality of customer nodes; and a channel scheduler for maintaining a set of weights corresponding to each of the customer nodes, identifying a minimum weight M from said set of weights, identifying a subset of said customer nodes having weights less than or equal to the sum of M and an offset K, determining a desirability metric value for each customer node in the subset, selecting from the subset a most desired customer node having the greatest desirability metric value, providing information corresponding to the most desired customer node to said channel element, and updating the set of weights.
While the embodiments disclosed herein are directed to methods and systems for allocating data transmission resources to subscribers through a forward channel in a data service network, the underlying principles have even broader applications to the allocation of resources among elements in a communication system generally. The disclosed embodiments are therefore intended to be exemplary and not limiting the scope of the claims. For example, principles described herein are applicable to communication networks in which the customer nodes compete for the ability to transmit data to a common node through a limited reverse transmission channel.